use PDG-parameter dictionary in Sherpa_i

Hi,

here's my proposed update to the implementation from !31892 (merged) (reverted in !32858 (merged)). Please review.

I've put in a WIP because this MR will change the top mass. However, we first need one more release with the old values to be consistent with the already prepared V+jets integrations, so this one should be merged afterwards.

cc/ @ewelina @lcorpe @fsiegert